The 22-year-old felt discomfort during a behind-closed-doors friendly this week, which has proved to be of enough concern to rule him out of today's game.
Colchester, playing their first game under new manager Tony Humes, are bidding to avoid a fifth straight League One defeat.
Josh Thompson is still out with a hamstring problem, but is said to be nearing fitness.
Walsall: O'Donnell, Kinsella, O'Connor, Downing, Taylor, Chambers, Flanagan, Clifford, Morris, Bradshaw, Manset
Subs: Holden, Baxendale, MacGillivray, Benning, Bakayoko, Henry, Forde
Colchester United: Walker, Clohessy, Eastman, Okuonghae, Gordon, Gilbey, Moncur, Szmodics, Massey, Sears, Watt
Subs: Wright, Eastmond, Lawrence, Vose, Kent, Smith, Lewington